ELECTRODE FOR ENERGY STORAGE DEVICE AND ENERGY STORAGE DEVICE USING THE SAME
Disclosed are an electrode for an energy storage device and an energy storage device using the same. The electrode for an energy storage device comprises a porous electrical conductive material and a plurality of Co—Mn composite oxide nanowires on the porous electrical conductive material. The energy storage device comprises an anode comprising the aforementioned electrode; a cathode; and an electrolyte between the anode and the cathode.
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The application relates to an electrode for energy storage device and energy storage device using the same, in particular to an electrode for an energy storage device having improved electrochemical performance and an energy storage device using the same.
DESCRIPTION OF BACKGROUND ARTDeveloping new energy storage devices for producing an electric current is necessary because of growing concerns over fossil fuel usage, global warming, and resource consumption. Among the energy storage devices, batteries and supercapacitors (SCs) are widely used. As the demand for the portable electronic devices increases, batteries have been widely used. Batteries and supercapacitors (SCs) utilize different mechanisms for electrical energy storage. Therefore, while batteries can store significantly more energy per unit volume than supercapacitors (SCs), supercapacitors (SCs) provide a larger volume power density, i.e., larger amount of power (time rate of energy transfer) per unit volume. This makes charge and discharge cycles of supercapacitors (SCs) much faster than batteries, and makes supercapacitors (SCs) suitable for applications that require a high current in a short time period, such as vehicles. However, to meet the commercial demand, improvement of the electrode is strongly needed in both the batteries and supercapacitors (SCs) for better electrochemical performance.
SUMMARY OF THE DISCLOSUREDisclosed are an electrode for an energy storage device and an energy storage device using the same. The electrode for an energy storage device comprises a porous electrical conductive material and a plurality of Co—Mn composite oxide nanowires on the porous electrical conductive material. The energy storage device comprises an anode comprising the aforementioned electrode; a cathode; and an electrolyte between the anode and the cathode.
In the present application, an electrode for an energy storage device and an energy storage device using the same are disclosed. The electrode for an energy storage device comprises Co—Mn composite oxide nanowires (NWs) on a porous electrical conductive material. The energy storage device can be batteries and supercapacitors (SCs), which both show good electrical performance.
The first embodiment of the present application illustrates an electrode for an energy storage device comprising Co—Mn composite oxide nanowires (NWs) on a porous electrical conductive material. In the present embodiment, Co—Mn composite oxide nanowires (NWs) comprise MnCo2O4 nanowires (NWs). The MnCo2O4 nanowires (NWs) are grown on a porous metal material. In the present embodiment, the porous metal material comprises foamed metal material, for example, foamed nickel (Ni). It is noted that other metal, for example, foamed copper (Cu) may also be used. In addition to the porous metal material, other porous electrical conductive material, for example, a carbon cloth which is constituted by carbon fibers may be used.
In the present embodiment, the method for forming the MnCo2O4 nanowires (NWs) on a porous Ni may be hydrothermal synthesis which comprises the following steps: First, a mixture solution comprising manganese nitrate tetrahydrate [Mn(NO3)2.4H2O], cobalt nitrate hexahydrate [Co(NO3)2.6H2O], ammonium fluoride (NH4F), and urea are provided. To be more specific, 0.02 mole of Mn(NO3)2.6H2O, 0.04 mole of Co(NO3)2.4H2O, 0.04 mole of NH4F, and 0.1 mole of urea are mixed and put inside an autoclave. Second, a porous Ni substrate, for example, a foamed Ni is partly immersed in the above mixture solution with a heat treatment at a temperature of 100-200° C. for a time period of 6-8 hours to grow MnCo2O4 nanowires (NWs), and then followed by annealing at a temperature of 300-400° C. for a time period of 2-4 hours. To be more specific, the heat treatment for the growth of MnCo2O4 NWs is at a temperature of 140° C. for a time period of 7 hours, and the anneal is at a temperature of 350° C. for a time period of 3 hours. In the present embodiment, the porous metal material comprises foamed metal material. It is noted the method to make the metal material porous can also be a de-alloying method, a powder sintering method, or an electrochemical method.
The second embodiment of the present application illustrates an energy storage device using the electrode comprising Co—Mn composite oxide NWs on porous electrical conductive material. In the present embodiment, a battery having an anode formed of MnCo2O4 NWs on foamed Ni illustrated in the above embodiment is illustrated. As shown in
The high capacity and good capacity retention can be attributed to the morphology and structure of the electrode comprising Co—Mn composite oxide NWs on porous electrical conductive material due to the following characteristics: (1) Co—Mn composite oxide NWs directly grown on porous electrical conductive material have high electronic conductivity because Co—Mn composite oxide NWs are firmly bound to the electrical conductive material, yielding significantly good adhesion and electrical contact; and (2) the line shape of the Co—Mn composite oxide NWs and the loose and open spaces between neighboring NWs because of the 3D configuration of the Co—Mn composite oxide NWs on porous electrical conductive material significantly enhance the contact area between electrolyte and Co—Mn composite oxide; therefore, the diffusion of the electrolyte is easier between the Co—Mn composite oxide NWs, and tolerance for the strain induced by the volume change during electrochemical reactions is increased because of porous electrical conductive material. These conditions lead to higher lithiation and delithiation efficiencies under electrolyte penetration.
The third embodiment of the present application illustrates another energy storage device using the electrode comprising Co—Mn composite oxide NWs on porous electrical conductive material. In the present embodiment, a supercapacitor (SC) having two electrodes formed of MnCo2O4 NWs on foamed Ni in the first embodiment is illustrated. As shown in
Such capacitive behavior may be attributed to the line shape of the Co—Mn composite oxide NWs and the loose and open spaces between neighboring NWs because of the 3D configuration of the Co—Mn composite oxide NWs on porous electrical conductive material, which facilitates fast electron transfer. NWs can function as transport channels for storing and transferring more electrical charges to the electrodes. The line shape NWs have larger surface areas that can increase the effective interfacial area for reaction. In general, excellent electrochemical performance could be derived from the features of the line shape Co—Mn composite oxide NWs on porous electrical conductive material, which significantly increase the number of electroactive sites. Furthermore, the direct growth of NWs on porous electrical conductive material ensures good mechanical adhesion as well as enhanced electrical contact between NWs and porous electrical conductive material.
The above-mentioned embodiments are only examples to illustrate the theory of the present invention and its effect, rather than be used to limit the present invention. Other alternatives and modifications may be made by a person of ordinary skill in the art of the present application without escaping the spirit and scope of the application, and are within the scope of the present application.
Claims
1. An electrode for an energy storage device, comprising a porous electrical conductive material and a plurality of Co—Mn composite oxide nanowires on the porous electrical conductive material.
2. The electrode for an energy storage device as claimed in claim 1, wherein the porous electrical conductive material comprises porous metal material.
3. The electrode for an energy storage device as claimed in claim 1, wherein the porous electrical conductive material comprises foamed Ni or foamed Cu.
4. The electrode for an energy storage device as claimed in claim 1, wherein the Co—Mn composite oxide nanowires comprise a line shape.
5. The electrode for an energy storage device as claimed in claim 1, wherein the plurality of Co—Mn composite oxide nanowires are directly formed on the porous electrical conductive material.
6. An energy storage device, comprising:
- an anode comprising a porous electrical conductive material and a plurality of Co—Mn composite oxide nanowires on the porous electrical conductive material;
- a cathode; and
- an electrolyte between the anode and the cathode.
7. The energy storage device as claimed in claim 6, wherein the energy storage device is a battery with a capacity larger than 1700 mAh/g.
8. The energy storage device as claimed in claim 6, wherein the energy storage device is a battery with an irreversible capacity loss less than 25% after a first charge-discharge cycle.
9. The energy storage device as claimed in claim 6, wherein the cathode comprises LiCoO2, LiFePO4, LiNiO2, LiMn2O4, or Li.
10. The energy storage device as claimed in claim 6, wherein the electrolyte comprises an organic solution.
11. The energy storage device as claimed in claim 6, wherein the electrolyte comprises LiPF6 (lithium hexafluorophosphate) dissolved in EC (ethylene carbonate) and DMC (dimethyl carbonate).
12. The energy storage device as claimed in claim 6, wherein the energy storage device is a supercapacitor, and the cathode comprises the same material as the anode.
13. The energy storage device as claimed in claim 12, wherein the electrolyte comprises a non-aqueous material.
14. The energy storage device as claimed in claim 12, wherein the electrolyte comprises a mixture of LiClO4 (lithium perchlorate) and PC (propylene carbonate).
15. The energy storage device as claimed in claim 12, wherein a capacitance of the energy storage device is larger than 210 F/g.
16. The energy storage device as claimed in claim 12, wherein a ratio of a capacitance after more than 1000 charge-discharge cycles to a first charge-discharge cycle is larger than 96%.
17. The energy storage device as claimed in claim 6, wherein the porous electrical conductive material comprises porous metal material.
18. The energy storage device as claimed in claim 6, wherein the porous electrical conductive material comprises foamed Ni or foamed Cu.
19. The energy storage device as claimed in claim 6, wherein the Co—Mn composite oxide nanowires comprise a line shape.
20. The energy storage device as claimed in claim 6, wherein the plurality of Co—Mn composite oxide nanowires are directly formed on the porous electrical conductive material.
Type: Application
Filed: Apr 15, 2014
Publication Date: Oct 15, 2015
Applicant: EPISTAR CORPORATION (Hsinchu)
Inventors: Saad MOHAMED (Taipei), Chih-Jung CHEN (Taipei), Ru-Shi LlU (Taipei), Shu-Fen HU (Taipei), Hsin-Mao LlU (Hsinchu), Ai-Sen LlU (Hsinchu)
Application Number: 14/253,469